Electronics question for Homelink module

[dpinvidic]

My #1 button seems to lose its training and I have to re-train.
So I ordered a new module and removed the orig. module.

DETAILS: The module only has a three wire connection. One is ground, the other is always hot
I have the digital dash that displays when a Homelink channel is transmitting & when it is training.

QUESTION: How does the display know which channel is xmiting and training? If it was a CAN bus connection, there would be a two wire connection.

Does anyone know how this circuit works?

Thanks,

Dan

 

[Tach_tech]

The compass/home link module uses the LIN bus system which only requires 1 wire. So the 3 pins are fused b+,ground and LIN bus. LIN bus is a slower, cheaper system, also less reliable but that’s why it’s used on a lot of the less significant components.